Curated Optogenetic Publication Database

Search precisely and efficiently by using the advantage of the hand-assigned publication tags that allow you to search for papers involving a specific trait, e.g. a particular optogenetic switch or a host organism.

Showing 1 - 25 of 65 results
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1.

Programmable RNA base editing with photoactivatable CRISPR-Cas13.

blue Magnets HEK293T HeLa HT-1080 MCF7 mouse in vivo Neuro-2a Nucleic acid editing
Nat Commun, 22 Jan 2024 DOI: 10.1038/s41467-024-44867-2 Link to full text
Abstract: CRISPR-Cas13 is widely used for programmable RNA interference, imaging, and editing. In this study, we develop a light-inducible Cas13 system called paCas13 by fusing Magnet with fragment pairs. The most effective split site, N351/C350, was identified and found to exhibit a low background and high inducibility. We observed significant light-induced perturbation of endogenous transcripts by paCas13. We further present a light-inducible base-editing system, herein called the padCas13 editor, by fusing ADAR2 to catalytically inactive paCas13 fragments. The padCas13 editor enabled reversible RNA editing under light and was effective in editing A-to-I and C-to-U RNA bases, targeting disease-relevant transcripts, and fine-tuning endogenous transcripts in mammalian cells in vitro. The padCas13 editor was also used to adjust post-translational modifications and demonstrated the ability to activate target transcripts in a mouse model in vivo. We therefore present a light-inducible RNA-modulating technique based on CRISPR-Cas13 that enables target RNAs to be diversely manipulated in vitro and in vivo, including through RNA degradation and base editing. The approach using the paCas13 system can be broadly applicable to manipulating RNA in various disease states and physiological processes, offering potential additional avenues for research and therapeutic development.
2.

Development of an optogenetic gene expression system in Lactococcus lactis using a split photoactivatable T7 RNA polymerase.

blue Magnets L. lactis Transgene expression
bioRxiv, 6 Jan 2024 DOI: 10.1101/2024.01.05.574370 Link to full text
Abstract: Cellular processes can be modulated by physical means, such as light, which offers advantages over chemically inducible systems with respect to spatiotemporal control. Here we introduce an optogenetic gene expression system for Lactococcus lactis that utilizes a split T7 RNA polymerase linked to two variants of the Vivid regulators. Depending on the chosen photoreceptor variant, either ‘Magnets’ or ‘enhanced Magnets’, this system can achieve either high protein expression levels or low basal activity in the absence of light, exhibiting a fold induction close to 30, rapid expression kinetics, and heightened light sensitivity. This system functions effectively in liquid cultures and within cells embedded in hydrogel matrices, highlighting its potential in the development of novel engineered living materials capable of responding to physical stimuli such as light. The optogenetic component of this system is highly customizable, allowing for the adjustment of expression patterns through modifications to the promoters and/or engineered T7 RNA polymerase variants. We anticipate that this system can be broadly adapted to other Gram-positive hosts with minimal modifications required.
3.

Dynamic Multiplexed Control and Modeling of Optogenetic Systems Using the High-Throughput Optogenetic Platform, Lustro.

blue CRY2/CIB1 EL222 Magnets S. cerevisiae Transgene expression
bioRxiv, 20 Dec 2023 DOI: 10.1101/2023.12.19.572411 Link to full text
Abstract: The ability to control cellular processes using optogenetics is inducer-limited, with most optogenetic systems responding to blue light. To address this limitation, we leverage an integrated framework combining Lustro, a powerful high-throughput optogenetics platform, and machine learning tools to enable multiplexed control over blue light-sensitive optogenetic systems. Specifically, we identify light induction conditions for sequential activation as well as preferential activation and switching between pairs of light-sensitive spit transcription factors in the budding yeast, Saccharomyces cerevisiae. We use the high-throughput data generated from Lustro to build a Bayesian optimization framework that incorporates data-driven learning, uncertainty quantification, and experimental design to enable the prediction of system behavior and the identification of optimal conditions for multiplexed control. This work lays the foundation for designing more advanced synthetic biological circuits incorporating optogenetics, where multiple circuit components can be controlled using designer light induction programs, with broad implications for biotechnology and bioengineering.
4.

Photoactivation of LOV domains with chemiluminescence.

blue BcLOV4 iLID Magnets VVD in vitro Extracellular optogenetics
Chem Sci, 11 Dec 2023 DOI: 10.1039/d3sc04815b Link to full text
Abstract: Optogenetics has opened new possibilities in the remote control of diverse cellular functions with high spatiotemporal precision using light. However, delivering light to optically non-transparent systems remains a challenge. Here, we describe the photoactivation of light-oxygen-voltage-sensing domains (LOV domains) with in situ generated light from a chemiluminescence reaction between luminol and H2O2. This activation is possible due to the spectral overlap between the blue chemiluminescence emission and the absorption bands of the flavin chromophore in LOV domains. All four LOV domain proteins with diverse backgrounds and structures (iLID, BcLOV4, nMagHigh/pMagHigh, and VVDHigh) were photoactivated by chemiluminescence as demonstrated using a bead aggregation assay. The photoactivation with chemiluminescence required a critical light-output below which the LOV domains reversed back to their dark state with protein characteristic kinetics. Furthermore, spatially confined chemiluminescence produced inside giant unilamellar vesicles (GUVs) was able to photoactivate proteins both on the membrane and in solution, leading to the recruitment of the corresponding proteins to the GUV membrane. Finally, we showed that reactive oxygen species produced by neutrophil like cells can be converted into sufficient chemiluminescence to recruit the photoswitchable protein BcLOV4-mCherry from solution to the cell membrane. The findings highlight the utility of chemiluminescence as an endogenous light source for optogenetic applications, offering new possibilities for studying cellular processes in optically non-transparent systems.
5.

Design and Engineering of Light-Induced Base Editors Facilitating Genome Editing with Enhanced Fidelity.

blue Magnets E. coli HEK293T Nucleic acid editing
Adv Sci (Weinh), 1 Dec 2023 DOI: 10.1002/advs.202305311 Link to full text
Abstract: Base editors, which enable targeted locus nucleotide conversion in genomic DNA without double-stranded breaks, have been engineered as powerful tools for biotechnological and clinical applications. However, the application of base editors is limited by their off-target effects. Continuously expressed deaminases used for gene editing may lead to unwanted base alterations at unpredictable genomic locations. In the present study, blue-light-activated base editors (BLBEs) are engineered based on the distinct photoswitches magnets that can switch from a monomer to dimerization state in response to blue light. By fusing the N- and C-termini of split DNA deaminases with photoswitches Magnets, efficient A-to-G and C-to-T base editing is achieved in response to blue light in prokaryotic and eukaryotic cells. Furthermore, the results showed that BLBEs can realize precise blue light-induced gene editing across broad genomic loci with low off-target activity at the DNA- and RNA-level. Collectively, these findings suggest that the optogenetic utilization of base editing and optical base editors may provide powerful tools to promote the development of optogenetic genome engineering.
6.

A programmable protease-based protein secretion platform for therapeutic applications.

blue red BphS CRY2/CIB1 Magnets PhyA/FHY1 Hana3A HEK293T hMSCs mouse IPSCs Control of vesicular transport
Nat Chem Biol, 23 Oct 2023 DOI: 10.1038/s41589-023-01433-z Link to full text
Abstract: Cell-based therapies represent potent enabling technologies in biomedical science. However, current genetic control systems for engineered-cell therapies are predominantly based on the transcription or translation of therapeutic outputs. Here we report a protease-based rapid protein secretion system (PASS) that regulates the secretion of pretranslated proteins retained in the endoplasmic reticulum (ER) owing to an ER-retrieval signal. Upon cleavage by inducible proteases, these proteins are secreted. Three PASS variants (chemPASS, antigenPASS and optoPASS) are developed. With chemPASS, we demonstrate the reversal of hyperglycemia in diabetic mice within minutes via drug-induced insulin secretion. AntigenPASS-equipped cells recognize the tumor antigen and secrete granzyme B and perforin, inducing targeted cell apoptosis. Finally, results from mouse models of diabetes, hypertension and inflammatory pain demonstrate light-induced, optoPASS-mediated therapeutic peptide secretion within minutes, conferring anticipated therapeutic benefits. PASS is a flexible platform for rapid delivery of therapeutic proteins that can facilitate the development and adoption of cell-based precision therapies.
7.

Comprehensive Screening of a Light-Inducible Split Cre Recombinase with Domain Insertion Profiling.

blue Magnets E. coli Transgene expression
ACS Synth Biol, 3 Oct 2023 DOI: 10.1021/acssynbio.3c00328 Link to full text
Abstract: Splitting proteins with light- or chemically inducible dimers provides a mechanism for post-translational control of protein function. However, current methods for engineering stimulus-responsive split proteins often require significant protein engineering expertise and the laborious screening of individual constructs. To address this challenge, we use a pooled library approach that enables rapid generation and screening of nearly all possible split protein constructs in parallel, where results can be read out by using sequencing. We perform our method on Cre recombinase with optogenetic dimers as a proof of concept, resulting in comprehensive data on the split sites throughout the protein. To improve the accuracy in predicting split protein behavior, we develop a Bayesian computational approach to contextualize errors inherent to experimental procedures. Overall, our method provides a streamlined approach for achieving inducible post-translational control of a protein of interest.
8.

Light-induced trapping of endogenous proteins reveals spatiotemporal roles of microtubule and kinesin-1 in dendrite patterning of Drosophila sensory neurons.

blue CRY2/CIB1 CRY2/CRY2 CRY2olig Magnets D. melanogaster in vivo Control of cytoskeleton / cell motility / cell shape
bioRxiv, 2 Oct 2023 DOI: 10.1101/2023.09.30.560303 Link to full text
Abstract: Animal development involves numerous molecular events, whose spatiotemporal properties largely determine the biological outcomes. Conventional methods for studying gene function lack the necessary spatiotemporal resolution for precise dissection of developmental mechanisms. Optogenetic approaches are powerful alternatives, but most existing tools rely on exogenous designer proteins that produce narrow outputs and cannot be applied to diverse or endogenous proteins. To address this limitation, we developed OptoTrap, a light-inducible protein trapping system that allows manipulation of endogenous proteins tagged with GFP or split GFP. This system turns on fast and is reversible in minutes or hours. We generated OptoTrap variants optimized for neurons and epithelial cells and demonstrate effective trapping of endogenous proteins of diverse sizes, subcellular locations, and functions. Furthermore, OptoTrap allowed us to instantly disrupt microtubules and inhibit the kinesin-1 motor in specific dendritic branches of Drosophila sensory neurons. Using OptoTrap, we obtained direct evidence that microtubules support the growth of highly dynamic dendrites. Similarly, targeted manipulation of Kinesin heavy chain revealed differential spatiotemporal requirements of kinesin-1 in the patterning of low- and high-order dendritic branches, suggesting that different cargos are needed for the growth of these branches. OptoTrap allows for precise manipulation of endogenous proteins in a spatiotemporal manner and thus holds great promise for studying developmental mechanisms in a wide range of cell types and developmental stages.
9.

Spatiotemporal, optogenetic control of gene expression in organoids.

blue CRY2/CIB1 Magnets HEK293T human IPSCs Endogenous gene expression Nucleic acid editing
Nat Methods, 21 Sep 2023 DOI: 10.1038/s41592-023-01986-w Link to full text
Abstract: Organoids derived from stem cells have become an increasingly important tool for studying human development and modeling disease. However, methods are still needed to control and study spatiotemporal patterns of gene expression in organoids. Here we combined optogenetics and gene perturbation technologies to activate or knock-down RNA of target genes in programmable spatiotemporal patterns. To illustrate the usefulness of our approach, we locally activated Sonic Hedgehog (SHH) signaling in an organoid model for human neurodevelopment. Spatial and single-cell transcriptomic analyses showed that this local induction was sufficient to generate stereotypically patterned organoids and revealed new insights into SHH's contribution to gene regulation in neurodevelopment. With this study, we propose optogenetic perturbations in combination with spatial transcriptomics as a powerful technology to reprogram and study cell fates and tissue patterning in organoids.
10.

Photoactivatable base editors for spatiotemporally controlled genome editing in vivo.

blue AsLOV2 CRY2/CIB1 Magnets HEK293T mouse in vivo Transgene expression Nucleic acid editing
Biomaterials, 13 Sep 2023 DOI: 10.1016/j.biomaterials.2023.122328 Link to full text
Abstract: CRISPR-based base editors (BEs) are powerful tools for precise nucleotide substitution in a wide range of organisms, but spatiotemporal control of base editing remains a daunting challenge. Herein, we develop a photoactivatable base editor (Mag-ABE) for spatiotemporally controlled genome editing in vivo for the first time. The base editing activity of Mag-ABE can be activated by blue light for spatiotemporal regulation of both EGFP reporter gene and various endogenous genes editing. Meanwhile, the Mag-ABE prefers to edit A4 and A5 positions rather than to edit A6 position, showing the potential to decrease bystander editing of traditional adenine base editors. After integration with upconversion nanoparticles as a light transducer, the Mag-ABE is further applied for near-infrared (NIR) light-activated base editing of liver in transgenic reporter mice successfully. This study opens a promising way to improve the operability, safety, and precision of base editing.
11.

Diya – a universal light illumination platform for multiwell plate cultures.

blue green CcaS/CcaR CRY2/CIB1 EL222 Magnets VVD E. coli HEK293T HeLa S. cerevisiae Transgene expression
iScience, 9 Sep 2023 DOI: 10.1016/j.isci.2023.107862 Link to full text
Abstract: Recent progress in protein engineering has established optogenetics as one of the leading external non-invasive stimulation strategies, with many optogenetic tools being designed for in vivo operation. Characterization and optimization of these tools require a high-throughput and versatile light delivery system targeting micro-titer culture volumes. Here, we present a universal light illumination platform – Diya, compatible with a wide range of cell culture plates and dishes. Diya hosts specially-designed features ensuring active thermal management, homogeneous illumination, and minimal light bleedthrough. It offers light induction programming via a user-friendly custom-designed GUI. Through extensive characterization experiments with multiple optogenetic tools in diverse model organisms (bacteria, yeast and human cell lines), we show that Diya maintains viable conditions for cell cultures undergoing light induction. Finally, we demonstrate an optogenetic strategy for in vivo biomolecular controller operation. With a custom-designed antithetic integral feedback circuit, we exhibit robust perfect adaptation and light-controlled set-point variation using Diya.
12.

High-Throughput Optogenetics Experiments in Yeast Using the Automated Platform Lustro.

blue CRY2/CIB1 Magnets S. cerevisiae
J Vis Exp, 4 Aug 2023 DOI: 10.3791/65686 Link to full text
Abstract: Optogenetics offers precise control over cellular behavior by utilizing genetically encoded light-sensitive proteins. However, optimizing these systems to achieve the desired functionality often requires multiple design-build-test cycles, which can be time-consuming and labor-intensive. To address this challenge, we have developed Lustro, a platform that combines light stimulation with laboratory automation, enabling efficient high-throughput screening and characterization of optogenetic systems. Lustro utilizes an automation workstation equipped with an illumination device, a shaking device, and a plate reader. By employing a robotic arm, Lustro automates the movement of a microwell plate between these devices, allowing for the stimulation of optogenetic strains and the measurement of their response. This protocol provides a step-by-step guide on using Lustro to characterize optogenetic systems for gene expression control in the budding yeast Saccharomyces cerevisiae. The protocol covers the setup of Lustro's components, including the integration of the illumination device with the automation workstation. It also provides detailed instructions for programming the illumination device, plate reader, and robot, ensuring smooth operation and data acquisition throughout the experimental process.
13.

Opto-RhoGEFs, an optimized optogenetic toolbox to reversibly control Rho GTPase activity on a global to subcellular scale, enabling precise control over vascular endothelial barrier strength.

blue iLID Magnets hBE HeLa Signaling cascade control Control of cytoskeleton / cell motility / cell shape
Elife, 14 Jul 2023 DOI: 10.7554/elife.84364 Link to full text
Abstract: The inner layer of blood vessels consists of endothelial cells, which form the physical barrier between blood and tissue. This vascular barrier is tightly regulated and is defined by cell-cell contacts through adherens and tight junctions. To investigate the signaling that regulates vascular barrier strength, we focused on Rho GTPases, regulators of the actin cytoskeleton and known to control junction integrity. To manipulate Rho GTPase signaling in a temporal and spatial manner we applied optogenetics. Guanine-nucleotide exchange factor (GEF) domains from ITSN1, TIAM1, and p63RhoGEF, activating Cdc42, Rac, and Rho, respectively, were integrated into the optogenetic recruitment tool improved light-induced dimer (iLID). This tool allows for Rho GTPase activation at the subcellular level in a reversible and non-invasive manner by recruiting a GEF to a specific area at the plasma membrane, The membrane tag of iLID was optimized and a HaloTag was applied to gain more flexibility for multiplex imaging. The resulting optogenetically recruitable RhoGEFs (Opto-RhoGEFs) were tested in an endothelial cell monolayer and demonstrated precise temporal control of vascular barrier strength by a cell-cell overlap-dependent, VE-cadherin-independent, mechanism. Furthermore, Opto-RhoGEFs enabled precise optogenetic control in endothelial cells over morphological features such as cell size, cell roundness, local extension, and cell contraction. In conclusion, we have optimized and applied the optogenetic iLID GEF recruitment tool, that is Opto-RhoGEFs, to study the role of Rho GTPases in the vascular barrier of the endothelium and found that membrane protrusions at the junction region can rapidly increase barrier integrity independent of VE-cadherin.
14.

Lustro: High-Throughput Optogenetic Experiments Enabled by Automation and a Yeast Optogenetic Toolkit.

blue CRY2/CIB1 Magnets S. cerevisiae Transgene expression
ACS Synth Biol, 11 Jul 2023 DOI: 10.1021/acssynbio.3c00215 Link to full text
Abstract: Optogenetic systems use genetically encoded light-sensitive proteins to control cellular processes. This provides the potential to orthogonally control cells with light; however, these systems require many design-build-test cycles to achieve a functional design and multiple illumination variables need to be laboriously tuned for optimal stimulation. We combine laboratory automation and a modular cloning scheme to enable high-throughput construction and characterization of optogenetic split transcription factors in Saccharomyces cerevisiae. We expand the yeast optogenetic toolkit to include variants of the cryptochromes and enhanced Magnets, incorporate these light-sensitive dimerizers into split transcription factors, and automate illumination and measurement of cultures in a 96-well microplate format for high-throughput characterization. We use this approach to rationally design and test an optimized enhanced Magnet transcription factor with improved light-sensitive gene expression. This approach is generalizable to the high-throughput characterization of optogenetic systems across a range of biological systems and applications.
15.

A non-invasive photoactivatable split-Cre recombinase system for genome engineering in zebrafish.

blue Magnets zebrafish in vivo Nucleic acid editing
bioRxiv, 25 Jun 2023 DOI: 10.1101/2023.06.23.546268 Link to full text
Abstract: The cyclic recombinase (Cre)/loxP recombination system is a powerful technique for in vivo cell labeling and tracking. However, achieving high spatiotemporal precision in cell tracking using this system is challenging due to the requirement for reliable tissue-specific promoters. In contrast, light-inducible systems offer superior regional confinement, tunability and non-invasiveness compared to conventional lineage tracing methods. Here, we took advantage of the unique strengths of the zebrafish to develop an easy-to-use highly efficient, genetically encoded, Magnets-based, light-inducible transgenic Cre/loxP system. Our system relies on the reassembly of split Cre fragments driven by the affinity of the Magnets and is controlled by the zebrafish ubiquitin promoter. We demonstrate that our system does not exhibit phototoxicity or leakiness in the dark, and it enables efficient and robust Cre/loxP recombination in various tissues and cell types at different developmental stages through noninvasive illumination with blue light. Our newly developed tool is expected to open novel opportunities for light-controlled tracking of cell fate and migration in vivo.
16.

Synthetic Frizzled agonist and LRP antagonist for high-efficiency Wnt/β-catenin signaling manipulation in organoid cultures and in vivo.

blue Magnets HEK293T Signaling cascade control
bioRxiv, 22 Jun 2023 DOI: 10.1101/2023.06.21.545860 Link to full text
Abstract: Wnt/β-catenin signaling and its dysregulation play critical roles in the fate determination of stem cells and the pathology of various diseases. However, the application of translated Wnt ligand in regenerative medicine is hampered by its hydrophobicity and cross-reactivity with Frizzled (FZD) receptors. Here, we generate an engineered water-soluble, FZD subtype-specific agonist, RRP-pbFn, for high-efficiency Wnt/β-catenin signaling activation. In the absence of direct binding to LRP5/6, RRP-pbFn stimulates Wnt/β-catenin signaling more potently than surrogate Wnt. RRP-pbFn supports the growth of a variety of mouse and human organoids, and induces the expansion of liver and intestine progenitors in vivo. Meanwhile, we develop a synthetic LRP antagonist, RRP-Dkk1c, which exhibits heightened effectiveness in attenuating Wnt/β-catenin signaling activity compared to Dkk1, thereby abolishing the formation of CT26-derived colon cancer xenograft in vivo. Together, these two paired Wnt/β-catenin signaling manipulators hold great promise for biomedical research and potential therapeutics.
17.

Detecting Photoactivatable Cre-mediated Gene Deletion Efficiency in Escherichia coli.

blue Magnets E. coli Transgene expression
Bio Protoc, 5 Jun 2023 DOI: 10.21769/bioprotoc.4685 Link to full text
Abstract: Gene deletion is one of the standard approaches in genetics to investigate the roles and functions of target genes. However, the influence of gene deletion on cellular phenotypes is usually analyzed sometime after the gene deletion was introduced. Such lags from gene deletion to phenotype evaluation could select only the fittest fraction of gene-deleted cells and hinder the detection of potentially diverse phenotypic consequences. Therefore, dynamic aspects of gene deletion, such as real-time propagation and compensation of deletion effects on cellular phenotypes, still need to be explored. To resolve this issue, we have recently introduced a new method that combines a photoactivatable Cre recombination system and microfluidic single-cell observation. This method enables us to induce gene deletion at desired timings in single bacterial cells and to monitor their dynamics for prolonged periods. Here, we detail the protocol for estimating the fractions of gene-deleted cells based on a batch-culture assay. The duration of blue light exposure significantly affects the fractions of gene-deleted cells. Therefore, gene-deleted and non-deleted cells can coexist in a cellular population by adjusting the duration of blue light exposure. Single-cell observations under such illumination conditions allow the comparison of temporal dynamics between gene-deleted and non-deleted cells and unravel phenotypic dynamics provoked by gene deletion.
18.

Generation of a photocontrollable recombinant bovine parainfluenza virus type 3.

blue Magnets HEK293T MDBK Transgene expression
Microbiol Immunol, 6 Jan 2023 DOI: 10.1111/1348-0421.13052 Link to full text
Abstract: Bovine parainfluenza virus type 3 (BPIV3) is a promising vaccine vector against various respiratory virus infections, including the human PIV3, respiratory syncytial virus, and severe acute respiratory syndrome-coronavirus 2 infections. In this study, we combined the Magnet system and reverse genetic approach to generate photocontrollable BPIV3. An optically controllable Magnet gene was inserted into the H2 region of the BPIV3 large protein gene, which encodes an RNA-dependent RNA polymerase. The generated photocontrollable BPIV3 grew in specific regions of the cell sheet only when illuminated with blue light, suggesting that spatiotemporal control can aid in safe clinical applications of BPIV3.
19.

Enhancing the performance of Magnets photosensors through directed evolution.

blue Magnets E. coli HEK293T Transgene expression
bioRxiv, 15 Nov 2022 DOI: 10.1101/2022.11.14.516313 Link to full text
Abstract: Photosensory protein domains are the basis of optogenetic protein engineering. These domains originate from natural sources where they fulfill specific functions ranging from the protection against photooxidative damage to circadian rhythms. When used in synthetic biology, the features of these photosensory domains can be specifically tailored towards the application of interest, enabling their full exploitation for optogenetic regulation in basic research and applied bioengineering. In this work, we develop and apply a simple, yet powerful, directed evolution and high-throughput screening strategy that allows us to alter the most fundamental property of the widely used nMag/pMag photodimerization system: its light sensitivity. We identify a set of mutations located within the photosensory domains, which either increase or decrease the light sensitivity at sub-saturating light intensities, while also improving the dark-to-light fold change in certain variants. For some of these variants, photosensitivity and expression levels could be changed independently, showing that the shape of the light-activity dose-response curve can be tuned and adjusted. We functionally characterize the variants in vivo in bacteria on the single-cell and the population levels. We further show that a subset of these variants can be transferred into the mOptoT7 for gene expression regulation in mammalian cells. We demonstrate increased gene expression levels for low light intensities, resulting in reduced potential phototoxicity in long-term experiments. Our findings expand the applicability of the widely used Magnets photosensors by enabling a tuning towards the needs of specific optogenetic regulation strategies. More generally, our approach will aid optogenetic approaches by making the adaptation of photosensor properties possible to better suit specific experimental or bioprocess needs.
20.

Stable Transgenic Mouse Strain with Enhanced Photoactivatable Cre Recombinase for Spatiotemporal Genome Manipulation.

blue CRY2/CIB1 Magnets mouse in vivo primary mouse fibroblasts Nucleic acid editing
Adv Sci (Weinh), 20 Oct 2022 DOI: 10.1002/advs.202201352 Link to full text
Abstract: Optogenetic genome engineering is a powerful technology for high-resolution spatiotemporal genetic manipulation, especially for in vivo studies. It is difficult to generate stable transgenic animals carrying a tightly regulated optogenetic system, as its long-term expression induces high background activity. Here, the generation of an enhanced photoactivatable Cre recombinase (ePA-Cre) transgenic mouse strain with stringent light responsiveness and high recombination efficiency is reported. Through serial optimization, ePA-Cre is developed to generate a transgenic mouse line that exhibits 175-fold induction upon illumination. Efficient light-dependent recombination is detected in embryos and various adult tissues of ePA-Cre mice crossed with the Ai14 tdTomato reporter. Importantly, no significant background Cre activity is detected in the tested tissues except the skin. Moreover, efficient light-inducible cell ablation is achieved in ePA-Cre mice crossed with Rosa26-LSL-DTA mice. In conclusion, ePA-Cre mice offer a tightly inducible, highly efficient, and spatiotemporal-specific genome engineering tool for multiple applications.
21.

Blue Light Signaling Regulates Escherichia coli W1688 Biofilm Formation and l-Threonine Production.

blue Magnets E. coli Control of cell-cell / cell-material interactions
Microbiol Spectr, 27 Sep 2022 DOI: 10.1128/spectrum.02460-22 Link to full text
Abstract: Escherichia coli biofilm may form naturally on biotic and abiotic surfaces; this represents a promising approach for efficient biochemical production in industrial fermentation. Recently, industrial exploitation of the advantages of optogenetics, such as simple operation, high spatiotemporal control, and programmability, for regulation of biofilm formation has garnered considerable attention. In this study, we used the blue light signaling-induced optogenetic system Magnet in an E. coli biofilm-based immobilized fermentation system to produce l-threonine in sufficient quantity. Blue light signaling significantly affected the phenotype of E. coli W1688. A series of biofilm-related experiments confirmed the inhibitory effect of blue light signaling on E. coli W1688 biofilm. Subsequently, a strain lacking a blue light-sensing protein (YcgF) was constructed via genetic engineering, which substantially reduced the inhibitory effect of blue light signaling on biofilm. A high-efficiency biofilm-forming system, Magnet, was constructed, which enhanced bacterial aggregation and biofilm formation. Furthermore, l-threonine production was increased from 10.12 to 16.57 g/L during immobilized fermentation, and the fermentation period was shortened by 6 h. IMPORTANCE We confirmed the mechanism underlying the inhibitory effects of blue light signaling on E. coli biofilm formation and constructed a strain lacking a blue light-sensing protein; this mitigated the aforementioned effects of blue light signaling and ensured normal fermentation performance. Furthermore, this study elucidated that the blue light signaling-induced optogenetic system Magnet effectively regulates E. coli biofilm formation and contributes to l-threonine production. This study not only enriches the mechanism of blue light signaling to regulate E. coli biofilm formation but also provides a theoretical basis and feasibility reference for the application of optogenetics technology in biofilm-based immobilized fermentation systems.
22.

Dynamic cybergenetic control of bacterial co-culture composition via optogenetic feedback.

blue Magnets E. coli Transgene expression
Nat Commun, 16 Aug 2022 DOI: 10.1038/s41467-022-32392-z Link to full text
Abstract: Communities of microbes play important roles in natural environments and hold great potential for deploying division-of-labor strategies in synthetic biology and bioproduction. However, the difficulty of controlling the composition of microbial consortia over time hinders their optimal use in many applications. Here, we present a fully automated, high-throughput platform that combines real-time measurements and computer-controlled optogenetic modulation of bacterial growth to implement precise and robust compositional control of a two-strain E. coli community. In addition, we develop a general framework for dynamic modeling of synthetic genetic circuits in the physiological context of E. coli and use a host-aware model to determine the optimal control parameters of our closed-loop compositional control system. Our platform succeeds in stabilizing the strain ratio of multiple parallel co-cultures at arbitrary levels and in changing these targets over time, opening the door for the implementation of dynamic compositional programs in synthetic bacterial communities.
23.

Implementation of a Novel Optogenetic Tool in Mammalian Cells Based on a Split T7 RNA Polymerase.

blue Magnets VVD HEK293T Transgene expression
ACS Synth Biol, 3 Aug 2022 DOI: 10.1021/acssynbio.2c00067 Link to full text
Abstract: Optogenetic tools are widely used to control gene expression dynamics both in prokaryotic and eukaryotic cells. These tools are used in a variety of biological applications from stem cell differentiation to metabolic engineering. Despite some tools already available in bacteria, no light-inducible system currently exists to control gene expression independently from mammalian transcriptional and/or translational machineries thus working orthogonally to endogenous regulatory mechanisms. Such a tool would be particularly important in synthetic biology, where orthogonality is advantageous to achieve robust activation of synthetic networks. Here we implement, characterize, and optimize a new optogenetic tool in mammalian cells based on a previously published system in bacteria called Opto-T7RNAPs. The tool is orthogonal to the cellular machinery for transcription and consists of a split T7 RNA polymerase coupled with the blue light-inducible magnets system (mammalian OptoT7-mOptoT7). In our study we exploited the T7 polymerase's viral origins to tune our system's expression level, reaching up to an almost 20-fold change activation over the dark control. mOptoT7 is used here to generate mRNA for protein expression, shRNA for protein inhibition, and Pepper aptamer for RNA visualization. Moreover, we show that mOptoT7 can mitigate the gene expression burden when compared to another optogenetic construct. These properties make mOptoT7 a powerful new tool to use when orthogonality and viral RNA species (that lack endogenous RNA modifications) are desired.
24.

Optogenetic Maxwell Demon to Exploit Intrinsic Noise and Control Cell Differentiation Despite Time Delays and Extrinsic Variability.

blue Magnets in silico
bioRxiv, 5 Jul 2022 DOI: 10.1101/2022.07.05.498841 Link to full text
Abstract: The field of synthetic biology focuses on creating modular components which can be used to generate complex and controllable synthetic biological systems. Unfortunately, the intrinsic noise of gene regulation can be large enough to break these systems. Noise is largely treated as a nuisance and much past effort has been spent to create robust components that are less influenced by noise. However, extensive analysis of noise combined with ‘smart’ microscopy tools and optognenetic actuators can create control opportunities that would be difficult or impossible to achieve in the deterministic setting. In previous work, we proposed an Optogenetic Maxwell’s Demons (OMD) control problem and found that deep understanding and manipulation of noise could create controllers that break symmetry between cells, even when those cells share the same optogenetic input and identical gene regulation circuitry. In this paper, we extend those results to analyze (in silico) the robustness of the OMD control under changes in system volume, with time observation/actuation delays, and subject to parametric model uncertainties.
25.

Biochemical noise enables a single optogenetic input to control identical cells to track asymmetric and asynchronous reference signals.

blue Magnets in silico
bioRxiv, 5 Jul 2022 DOI: 10.1101/2022.07.05.498842 Link to full text
Abstract: Optogenetics is a powerful technology to control synthetic gene circuits using external and computer-programmable light inputs. Like all biological processes, these systems are subject to intrinsic noise that arises from the stochastic process of gene regulation at the single-cell level. Many engineers have sought to mitigate this noise by developing more complex embedded bio-circuits, but recent work has shown that noise-exploiting stochastic controllers could enable new control strategies that take advantage of noise, rather than working against it. These noise-exploiting controllers were initially proposed to solve a single-input-multi-output stationary control problem, where symmetry was broken in a means reminiscent to the concept of Maxwell’s Demon. In this paper, we extend those results and show through computation that transient, asymmetric, and asynchronous stochastic control of the single-input-multi-output (SIMO) control problem is posible to achieve by cycling through different controllers in time. We show that such a method is able control two cells to two different periodic fates with different frequencies and different phases despite the use of only one control input.
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